GRANTS PASS, Ore. -- Two different lightning-sparked wildfires grew quickly in hot and dry conditions in central Oregon on Thursday, prompting evacuation alerts.
Authorities said the Bridge 99 fire in the Cascade Range 20 miles north of Sisters tripled in size and threatened rural homes along the Metolius River from Allen Springs Campground to Lake Billy Chinook. A top-level evacuation advisory urged residents to leave their homes immediately.
In the Ochoco Mountains about 20 miles east of Prineville, the Bailey Butte Fire grew after getting into heavy timber in a wilderness area, prompting the Crook County Sheriff's office to advise residents of 27 homes in the Marks Creek area to leave.
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The evacuation area included the Mount Bachelor Academy, which was shut down by the state in 2009 amid allegations it mistreated troubled teens. U.S. Highway 26 remained closed at the Ochoco Summit near Mitchell.
They were among 13 large fires burning across Oregon, most of them sparked by lightning, from the eastern slopes of the Cascade Range to the Wallowa Mountains outside Joseph in the northeast corner of the state.
The Bridge 99 Fire burned through more than 1,800 acres on the Deschutes National Forest since it was started by a lightning strike Sunday. It was being managed as the Bridge 99 Complex along with the Bear Butte 2 fire, burning on more than 1,600 acres on the Mt. Jefferson Wilderness and the southern end of the Warm Springs Indian Reservation.
A section of the Pacific Crest Trail was closed, as well as some Forest Service roads.
Red flag warnings called for continued hot and dry weather.
Residents of the Three Rivers subdivision were told to be ready to leave on short notice, and several other subdivisions were told to be aware they could be advised to evacuate if things get worse.
On the Bailey Butte Fire, Crook County emergency services manager Michael Ryan said most people complied with the evacuation alert issued Thursday morning, but a few former wildland firefighters living in the Marks Creek area stayed behind.
He said the Bailey Butte Fire, part of the Waterman Complex, moved into heavy timber in a wilderness area Wednesday night and built up strength. It was moving to the southeast, flanking the Marks Creek area, where fire managers ordered additional crews to strengthen lines. The Oregon Department of Forestry reported more personnel were arriving to bolster the 500 people already fighting the fire, and hot, dry and breezy conditions were expected through the week.
The Bailey Butte Fire was reported 5 percent contained, at 2,105 acres several miles west of Mitchell. Two other fires in the complex were not threatening homes. The Toney Butte Fire was 50 percent contained after burning through 2,194 acres of grass, brush and juniper 6 miles west of Spray. The Junction Springs Fire was 90 percent contained at 20 acres.
Elsewhere in Oregon, several wildfires sparked by lightning storms in the past week were getting closer to containment.
Fire officials said the biggest of them, the Buzzard Complex, which burned through 282 square miles of grass and brush 45 miles northeast of Burns, is expected to be contained Friday.
The Moccasin Hill Fire was 55 percent contained after burning about four square miles of private forest land 4 miles north of Sprague River in Klamath County, including 17 homes in an off-the-grid subdivision. The cause of that fire was under investigation.